#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <math.h>
int main() {

    float s = 0, r = 0;
    scanf("%f", &r);
    s = 3.14 * (4.0 / 3) * pow(r, 3);
    printf("%.2f", s);
    return 0;
}